We like the American College of Sports Medicine brochure on selecting running-shoes . We think their advice is worthwhile and will help you narrow in on a good set of choices to try.
Additionally, there are studies that suggest that comfort may be the best predictor of injury, i.e., more comfort, less injury. This NY Times article explains it pretty well. We suggest an neurological assessment to determine which pair are comfortable and will benefit your performance most and likely reduce injury risk.